Authors: J.N. Tey, I.P.M. Wijaya, J. Wei, I. Rodriguez, S.G. Maisalkar
Affilation: Singapore Institute of Manufacturing Technology, Singapore
Pages: 187 - 190
Keywords: carbon nanotubes transistor, biosensor, opiate, heroin, metabolite
A label free, real time detection of opiate drug using the CNT liquid gated transistor is reported in this study. The device was fabricated using a facile method consists of two-step stamping and lamination process, as compared to the conventional fabrication process which relies highly on the complicated and high cost microfabrication technology. The proposed stamped device enables room temperature and large scale processing capability, which is potential for low cost, disposable, point-of-care diagnosis kit. In addition to the promising detection limit of ~ 100fg/ml for direct morphine-antibody detection, an amplification strategy was introduced to enhance the signal by incorporating Au nanoparticles to the morphine antibodies. Although Au nanoparticle has been widely used for signal enhancement in electrochemical measurement, no attempt in direct electrical detection in liquid gated transistor configuration was carried out before. The limit of detection for Au labeled morphine antibody detection was approximated to be ~ 1 fg/ml from the fitted regression equation, demonstrating a two orders of magnitude improvement. It is deduced that the negatively charged Au NPs induce positive doping to the channel hole concentration upon interacting with CNTs. This positive charge enhancement effect superimpose on the receptor-ligand interaction, resulting in larger signal amplification.